One thing I don't understand is why most people prefer the HP out to be on the top of the player instead of the bottom. Being on the top just adds unnecessary bending from the cable when you operate it in a normal position since the cable has to make its way to the listener, which is most of the time the person holding the DAP, which is obviously located at the bottom of the DAP. If their reason is mainly because of the convenience when putting the player in their pockets, well you can always put the player upside down in your pocket like I do with my cowon J3.
The line-out IMHO should be the one on the top because it will be used to connect to other devices that's more likely away from you. And the HP out should be pointing towards the user hence the bottom, because most likely the user of the headphones plugged in the HP out will be you, the owner of the device, or at least the one holding the device. HP out on top is like ideal for continuous demo-ing the product to other people but you still control the device lol.
I really think HP out for a DAP should be located at the bottom. I don't mind the smartphones though but for a DAP it really should be at the bottom. Please FiiO consider the X5's HP out to be at the bottom since it's still under development I hope you can still tweak and decide where to put the ports. Or at least give me one good reason why put it at the top other than it is more convenient to put it in the pocket. For me that's just a very lame reason.